Malignant melanoma: basic approach to clinicopathologic correlation.

To provide an overview of the clinicopathologic correlation of the various types of malignant melanoma, we describe and illustrate the four major types of these tumors and discuss the concept of microstaging for the prognostic evaluation of melanoma. The four major types of malignant melanoma are lentigo maligna melanoma, acral lentiginous melanoma, superficial spreading melanoma, and nodular melanoma. Lentigo maligna melanoma has irregular margins and usually occurs on sunlight-exposed skin in elderly patients. Acral lentiginous melanoma occurs on the hands and feet; it often demonstrates massive invasion when the vertical growth phase occurs. Among Caucasians, superficial spreading melanoma, which affects the trunk and extremities, is the most common malignant melanoma. These lesions are often variegated in color. Nodular melanomas are deeply pigmented and enlarge rapidly. For microstaging of malignant melanoma, determining Clark's level of tumor invasion or Breslow's thickness (from the top of the granular cell layer of the epidermis to the deepest extension of the tumor) is useful for assessment of prognosis. Establishing a definite diagnosis of malignant melanoma is feasible through clinicopathologic correlation. Microscopic measurement of the deepest levels of melanoma involvement in the skin provides a useful indication of the associated prognosis.